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Re: [Web MIDI API] send() timestamp

From: Jussi Kalliokoski <jussi.kalliokoski@gmail.com>
Date: Fri, 14 Dec 2012 22:12:51 +0200
Message-ID: <CAJhzemUOcJX1Fcy5RuKEqMtsgCiyNSq1zVNumezd8QpWL7o9ug@mail.gmail.com>
To: Marcos Caceres <marcos@marcosc.com>
Cc: public-audio@w3.org
On Fri, Dec 14, 2012 at 10:05 PM, Marcos Caceres <marcos@marcosc.com> wrote:

>
>
>
> On Friday, December 14, 2012 at 7:55 PM, Jussi Kalliokoski wrote:
>
> > Hi Marcos!
> >
> > On Fri, Dec 14, 2012 at 9:24 PM, Marcos Caceres <marcos@marcosc.com(mailto:
> marcos@marcosc.com)> wrote:
> > > Hi,
> > > I'm a bit confusedů why does the API require a timestamp relative to
> some time (i.e., performance.now())? For example:
> >
> >
> > This is to maintain symmetry with incoming messages, which have relative
> timestamps, e.g.
> >
> > // proxy
> > input.onmessage = function (e) {
> > output.send(e.data, e.timestamp)
> > }
> >
>
> Right, but that will just result in no waiting? (ie., just means 0 as
> timestamps in the past don't mean anything).
>

Not necessarily. Some platform MIDI APIs have an internal clock and allow
MIDI messages to be sent and processed ahead of time, so when you receive a
MIDI message, it might not be supposed to take effect immediately. The
timestamps being synchronized with DOMHRTF essentially let you
leverage/emulate this feature without exposing meaningless details about
the underlying API, such as its internal clock.

Cheers,
Jussi


> What am I not getting?
>
> --
> Marcos Caceres
>
>
>
>
Received on Friday, 14 December 2012 20:13:19 UTC

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